1. Field of the Invention
The present invention concerns a method for the transfer of an overhead conveyor carriage, which has been brought to the track-exchange area, from one track onto another by altering the height positions of the transfer wheels of the conveyor carriage in relation to the track. The invention also concerns an overhead conveyor system comprising a network of conveyor tracks and one or several conveyor carriages provided with transfer wheels, the network of conveyor tracks including track-exchange areas. The overhead conveyor system is particularly well suited, e.g., for the transfer of plate-shaped construction units cast of concrete between various processing points in the production plant.
2. Description of the Related Art
In the prior art, among other things, the overhead conveyor system described in the publication DE 2,243,032 includes a projecting rail, which is mounted on the conveyor carriage, which pivots around a vertical shaft, and on which an electric hoist can be run to the side of the conveyor carriage proper so as to engage or disengage a load. Thus, said prior-art system permits operation of the conveyor within a zone wider than the track line.
Also, in the prior art, an overhead conveyor system in accordance with the patent EP 0,110,196 (U.S. Pat. No. 4,561,359) is known, which is mainly suitable for the transfer of rather low-weight loads which can be lifted by hand. In said system the conveyor carriage can be suspended by its wheel sets between two parallel rails placed one above the other and, correspondingly, be detached from between the rails by altering the position of the suspension wheel sets by means of a vertical movement applied to the conveyor carriage and rotating the wheel sets around a horizontal axis. The downward movement that locks the wheel sets takes place by the effect of the weight of the carriage and of the load, and the upward detaching movement takes place by the effect of lifting by hand.
The method in accordance with the present invention is mainly characterized in that an overhead conveyor carriage that is provided with two sets of transfer wheels placed at a transverse distance from each other is brought to the track-exchange area, where a first track and a second track are placed at a specified distance and as parallel to each other, and that the height positions of the sets of transfer wheels of the conveyor carriage placed facing the first track and the second track are altered in such a way that the wheel sets in the carrying position are detached from the first track and the wheel sets in the detached position are placed into the carrying position on the second track. The conveyor system in accordance with the invention is characterized in that, in the track-exchange areas, the first track and the second track are placed side by side at a certain distance from each other and both of said tracks have running faces consisting of two guide rails placed at different heights, that the conveyor carriages are provided with two sets of transfer wheels placed at a transverse distance from each other, in which said wheel sets the wheels can be fitted into a grasping position against the running faces of the guide rails of either one of the tracks, and that the height positions of the sets of transfer wheels can be alternated between the grasping position and the detached position.
Advantages of the present invention over the invention in accordance with DE 2,243,032 are as follows:
no track switches are needed at the junction points between the alternative tracks (see DE 2,243,032, FIG. 1), PA1 when a load is transferred from one working site to the other, the lifting hook does not have to be coupled and uncoupled by hand in between, PA1 a possibility to transfer loads in narrow spaces lengthwise while suspended from two points, PA1 less heavy track support constructions, because no pivoting projection rail with heavy counterweight to permit lateral shifting is needed, PA1 three separate running rails are not needed.
In respect of its operations, the system of the patent EP 0,110,196 does not correspond to the system in accordance with the present invention, nor is it usable for the purposes of use described in the specification of the present invention.
In the overhead conveyor system in accordance with the present invention, by shifting the centre of gravity of the load and of the conveyor carriage horizontally in the transverse direction and by exchanging the positions of the sets of transfer wheels, alternatively grasping the adjoining running tracks, with each other, the conveyor carriage moving along a stationary conveyor track, together with the load that it has picked up, can be made to move onto the adjoining side track for the purpose of bypassing. If necessary, the conveyor carriage may also be made to "jump" onto another track, placed at the side in the location concerned, in other cases, as is chosen, without any track switch member that alters its position of operation or that it otherwise displaceable.
The accompanying FIGS. 1 to 18 illustrate an overhead conveyor system in accordance with the present invention: